This application claims the benefit of Korean Patent Application No. 2001-73960, filed Nov. 26, 2001 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a paper-feed roller, which is employed in an office automation machine, such as a photocopier, a printer, a facsimile machine, etc, to supply and discharge to-be-copied or to-be-printed paper (herein below called xe2x80x98paperxe2x80x99), and a fabrication method thereof, and more particularly, to a paper-feed roller and a fabrication method of producing the paper-feed roller with an economical effect in a fabrication cost and preventing a slippage of paper or a paper jam that is caused by a heat distortion and an abrasion occurring on a surface of a long time operated paper-feed roller.
2. Description of the Related Art
Generally, an office automation machine, such as a photocopier, a printer, a facsimile machine, etc, has been expected to print an image on a sheet of paper at a higher speed. Accordingly, a paper feed roller employed in the office automation machine is required to supply, convey, and discharge the paper at the higher speed while performing a basic function of preventing slipping of the paper or a paper jam.
FIG. 1 shows a general paper-feed roller 10. The paper-feed roller 10 includes a shaft 1 and a plurality of smaller rollers 2. The smaller rollers 2 are disposed around the shaft 1 and spaced from each other by a predetermined distance. The shaft 1 is generally made of a metal such as aluminum and stainless. The smaller rollers 2 are made of a material, such as rubber, that has a high surface friction, thereby preventing the paper from slipping away from the smaller rollers 2. Nitrile rubber, urethane rubber, epichlorohydrin rubber, silicone rubber, ethylenepropylene rubber, acryl rubber, butyl rubber, etc, are largely used as the rubber material.
The paper-feed roller 10 made of the rubber can supply, convey and discharge the paper at the high speed using the high surface friction in an early stage of use of the paper-feed roller 10. However, a long time use or a high-speed rotation of the paper-feed roller 10 causes a friction heat to occur on a surface of the paper-feed roller 10, and thus the surface of the paper-feed roller 10 deteriorates. Accordingly, the surface friction is reduced such that the paper easily slips away from the paper-feed roller 10, and there also occurs a paper jam. Especially, in a case of a photo printer printing a full image, there may occur an image distortion due to the slipping of the paper.
Also, if the paper-feed roller 10 has a low surface roughness, a surface abrasion is easy to occur. Therefore, a space between the smaller rollers 2 becomes wider as the paper-feed roller 10 conveys the paper, for example, approximately 20,000 sheets, for a predetermined time.
In order to solve the above problems of the lowered surface friction and the surface abrasion of the paper-feed roller 10, a method has been proposed that a pipe made of stainless or carbon steel is used as the shaft, and that a ceramic coating layer is formed on a surface of the pipe. This method may overcome the shortcoming of the lowered surface friction or the surface abrasion in the conventional rubber paper-feed roller 10, but has a difficulty in installing a gear or a gear train to the paper-feed roller 10 to transmit a rotation power to the paper-feed roller 10 due to the use of the pipe as the shaft.
The present invention has been developed in order to solve the above and other problems in the related art. Accordingly, it is an object to provide a paper-feed roller and a fabrication method capable of providing an economical effect in a fabrication cost and preventing a slippage of paper or a paper jam that is caused by a heat distortion or a abrasion occurring on a surface of a long time operated roller, by forming a plastic roller along a general shaft and forming a ceramic coating layer on a surface of the plastic roller to contact the paper.
Additional objects and advantageous of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
In order to achieve the above and other objects, a paper-feed roller according to an embodiment of the present invention includes a shaft and at least one roller disposed along the shaft, wherein the roller is made of plastic, and a surface of the roller to contact the paper is coated with a ceramic coating layer.
In an embodiment of the present invention, the shaft is made of stainless steel, and the roller is made of any one of ABC, PC, an epoxy resin, a urethane resin, a polyamide resin, a polyvinyl chloride resin, a polyethylene resin, a polyester resin, or a phenol resin. The ceramic coating layer is made of any one or any combination of Al2O3, SiO2, ZrO2, SiC, TiC, TaC, B4C, Cr2C2, Si3N4, BN, TiN, AlN, TiB2, ZrB2, TiO2, and MgF2. A thickness of the ceramic coating layer is equal to or below 2,000 xcexcm. Also, the roller has corners formed at both ends thereof to prevent the ceramic coating layer from being peeled off from the surface of the roller. The ceramic coating layer has a surface friction coefficient of 1.1xc2x110% that is obtained by a ASTM D 1894-75 method when XEROX 4200 paper is conveyed at a speed of 500 mm/min.
According to the present invention, a method of fabricating a paper-feed roller includes forming at least one plastic roller along a metallic shaft by a molding process and forming a ceramic coating layer of a thickness equal to or below 2,000 xcexcm on a surface of the plastic roller.
The forming of the ceramic coating layer includes jetting a processing gas including a ceramic particle onto the surface of the roller from a cathode spaced-apart from the roller by 10-20 mm in conditions of a degree of vacuum ranges from 10xe2x88x922 to 10xe2x88x923 torr, a voltage equal to or below 0.1 W/cm2, and a low pressure plasma of the processing gas being an argon gas and an oxygen gas.
The ceramic particle consists of any one or any combination of Al2O3, SiO2, ZrO2, SiC, TiC, TaC, B4C, Cr2C2, Si3N4, BN, TiN, AlN, TiB2, ZrB2, TiO2, and MgF2.
The method of fabricating the paper-feed roller further includes grinding the surface of the roller to an extent of roughness that is equal to or below 2,000 xcexcm to eliminate a foreign material from the surface of the plastic roller and achieve an easy adhesiveness of the ceramic coating layer to the surface of the plastic roller.